Cassette having elastomeric clamping ribs

ABSTRACT

A cassette having a molded flow channel contained on an elastomeric sheet that is bonded or mechanically attached to a rigid substrate. A surgical console contains a cassette receiving area having a pump head with rollers that are mounted radially from the axis of rotation of the pump motor and compress the elastomeric flow channels against the rigid substrate. The cassette is held in place against the pump head by a latching mechanism that draws the cassette against the pump head. The periphery of the elastomeric sheet contains a raised ridge or boss integrally formed as part of the elastomeric sheet at or near the area(s) of the elastomeric sheet that is/are subject to high transient or static pressures. The ridge allows the elastomeric sheet to be firmly pressed against the cassette receiving portion of the surgical console, yet still allow the cassette to be drawn against the pump head. The firm engagement of the sheet ridge against the cassette receiving portion of the surgical console helps to ensure that the elastomeric sheet does not become dislodged when the cassette is exposed to high transient pressures.

BACKGROUND OF THE INVENTION

The present invention relates generally to peristaltic pumps and morespecifically to fluidic cassettes used in ophthalmic surgical equipment.

Most prior art peristaltic pumps work by compressing or squeezing alength of flexible tubing (sometimes between a fixed race) using arotating roller head. As the roller head rotates, the rollers pinch offa portion of the tubing and push any fluid trapped in the tubing betweenthe rollers in the direction of rotation. Peristaltic pumps are widelyused in medical applications because of their predictable, constant flowproperties. These prior art systems, however, typically require manualconnection of the pump tube segment around the rotating roller head.

Prior art peristaltic pumps using rotating roller heads also typicallyimpart unwanted pressure pulsations. Several pulsation damping deviceshave been developed to address this problem (see e.g., U.S. Pat. No.4,921,477 (Davis)).

Another prior art pump is disclosed in U.S. Pat. No. 6,293,926 B1(Sorensen, et al.) describes a peristaltic pump having a molded flowchannel contained on an elastomeric sheet that is bonded or mechanicallyattached to a rigid substrate. The pump head rollers are mountedradially from the axis of rotation of the pump motor and compress theelastomeric flow channels against the rigid substrate. The commercialembodiment of the invention described in this patent is sold as theINFINITI® Vision System by Alcon Laboratories, Inc., Fort Worth, Tex.This surgical console uses a Fluid Management System or cassette whereinthe elastomeric sheet is friction fit into the rigid substrate withoutthe use of any adhesives Such a construction method has proven to beextremely reliable, but this commercial system is intended primarily forcataract surgery and has no other source of vacuum other than theperistaltic pump. Therefore, the fluidic system is exposed primarily tonegative pressure or vacuum and is not exposed to transient highpositive pressures, such as are encountered during a reflux operation inposterior segment surgical procedures using a venturi pump as theprimary source of vacuum. These high positive pressures can be as highas 700 mm Hg and have the potential to cause failure at theelastomer/substrate interface if a friction fit construction techniqueis used.

Accordingly, a need continues to exist for a surgical cassette thatreduces the potential for cassette failure under transient positivepressures.

BRIEF SUMMARY OF THE INVENTION

The present invention improves upon prior art cassettes by providing acassette having a molded flow channel contained on an elastomeric sheetthat is bonded or mechanically attached to a rigid substrate. A surgicalconsole contains a cassette receiving area having a pump head withrollers that are mounted radially from the axis of rotation of the pumpmotor and compress the elastomeric flow channels against the rigidsubstrate. The cassette is held in place against the pump head by alatching mechanism that draws the cassette against the pump head. Theelastomeric sheet contains a raised ridge or boss integrally formed aspart of the elastomeric sheet at or near the area(s) of the elastomericsheet that is/are subject to high transient or static pressures. Theridge allows the elastomeric sheet to be firmly pressed against thecassette receiving portion of the surgical console, yet still allow thecassette to be drawn against the pump head. The firm engagement of thesheet ridge against the cassette receiving portion of the surgicalconsole helps to ensure that the elastomeric sheet does not becomedislodged when the cassette is exposed to high transient pressures.

One objective of the present invention is to provide a peristaltic pumpthat uses molded elastomeric flow channels.

Another objective of the present invention is to provide a peristalticpump having radially oriented pump rollers.

Yet another objective of the present invention is to provide aperistaltic pump having pump rollers that compress elastomeric flowchannels against a rigid substrate.

Still another objective of the present invention is to provide acassette having an elastomeric sheet fitting to a rigid substrate.

Still another objective of the present invention is to provide acassette having an elastomeric sheet fitting to a rigid substrate sothat the elastomeric sheet does not become dislodged when the cassetteis exposed to high transient pressures.

These and other advantages and objectives of the present invention willbecome apparent from the detailed description, drawings and claims thatfollow.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front perspective view of the cassette of the presentinvention.

FIG. 2 is a rear perspective view of the cassette of the presentinvention.

FIG. 3 is a schematic representation of the surgical cassette of thepresent invention installed in a surgical console.

FIG. 4 is a rear perspective view of the pump elastomer sheet used onthe cassette of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

As best seen in FIGS. 1-3, cassette 10 of the present inventiongenerally includes body 11 having front face 12 containing a pluralityof fluidic connections 14 for fluidically connecting cassette 10 toinfusion fluid source 20 and surgical handpiece 22 used during asurgical procedure. Cassette 10 may also include handle 16 for assistingin installing and removing cassette 10 from surgical console 24. As bestseen in FIG. 2, cassette 10 has rear face 18 opposite front face 12 andadapted for mechanical and fluidic interaction with surgical console 24.Frictionally mounted on rear face 18 of cassette 10 are a plurality ofelastomeric interface-forming sheets, such as pneumatics elastomer 25,infusion elastomer 26, aspiration elastomer 28, valve elastomer 100 andpump elastomer 30. Cassette 10 is mounted within console 24 so that pumpelastomer 30 is pressed against pump mechanism 32 mounted in console 24by latches 38. Cassette 10 may be molded from any suitable material,such as thermoplastic and elastomers 25, 26, 28 and 30 may be moldedfrom any suitable elastomer, such as silicone rubber.

As best seen in FIG. 4, pump elastomer 30 is generally circular,approximating the size and shape of the roller head (not shown) mountedto pump mechanism 32. Pump elastomer 30 contains pumping channel 34 thatinteracts with pump mechanism 32 to provide peristaltic pumping actionthrough cassette 10. The operation of cassette 10 and pump mechanism 32is more fully described in U.S. Pat. No. 6,293,926 B1 (Sorensen, etal.), the contents of which being incorporated herein by reference. Inorder to assure that pump elastomers 25, 26, 28, 30 and 100 are firmlypressed against console 24, thereby helping to reduce the likelihoodthat elastomers 25, 26, 28, 30 and 100 can be dislodged from cassette 10when exposed to high transient pressures, elastomers 25, 26, 28 and 30contain raised ribs or bosses 36 extending around the entire areas ofelastomers 25, 26, 28, 30 and 100 that are subject to high transient orstatic pressures. Ribs 36 are compressed when latches 38 press cassette10 into console 24, thereby helping to prevent any movement ofelastomers 25, 26, 28, 30 and 100.

This description is given for purposes of illustration and explanation.It will be apparent to those skilled in the relevant art thatmodifications may be made to the invention as herein described withoutdeparting from its scope or spirit.

1. A cassette, comprising: a) a body having an exterior; b) a firstrelatively flexible elastomeric sheet attached to the body, the firstsheet containing at least one molded pumping channel projectingoutwardly from the exterior of the body; and c) a raised rib extendingalong the entire area of the first elastomeric sheet that is subject tohigh transient or static pressures.
 2. The cassette of claim 1 furthercomprising at least a second flexible elastomeric sheet, the secondelastomeric sheet having a raised rib extending along the entire area ofthe second elastomeric sheet that is subject to high transient or staticpressures.
 3. The cassette of claim 2 wherein the second flexibleelastomeric sheet comprises a pneumatics elastomer.
 4. The cassette ofclaim 2 wherein the second flexible elastomeric sheet comprises anaspiration elastomer.
 5. The cassette of claim 2 wherein the secondflexible elastomeric sheet comprises a pump elastomer.
 6. The cassetteof claim 2 wherein the second flexible elastomeric sheet comprises avalve elastomer.
 7. The cassette of claim 2 wherein the second flexibleelastomeric sheet comprises an infusion elastomer.
 8. A cassette,comprising: a) a body having an exterior; b) a first relatively flexibleelastomeric sheet attached to the body, the first flexible sheetprojecting outwardly from the exterior of the body; and c) a raised ribextending along the entire area of the first flexible elastomeric sheetthat is subject to high transient or static pressures.
 9. The cassetteof claim 8 further comprising at least a second flexible elastomericsheet, the second elastomeric sheet having a raised rib extending alongthe entire area of the second elastomeric sheet that is subject to hightransient or static pressures.
 10. The cassette of claim 9 wherein thesecond flexible elastomeric sheet comprises a pneumatics elastomer. 11.The cassette of claim 9 wherein the second flexible elastomeric sheetcomprises an aspiration elastomer.
 12. The cassette of claim 9 whereinthe second flexible elastomeric sheet comprises a pump elastomer. 13.The cassette of claim 9 wherein the second flexible elastomeric sheetcomprises a valve elastomer.
 14. The cassette of claim 9 wherein thesecond flexible elastomeric sheet comprises at least one molded pumpingchannel.
 15. The cassette of claim 9 wherein the second flexibleelastomeric sheet comprises a valve elastomer.